In 2000, the pioneering underwater archaeologist Franck Goddio made one of the greatest ever submerged discoveries.

He found evidence that the remains he had found off the coast of Egypt were from Thonis-Heracleion, an ancient Egyptian port lost without trace.

Before the foundation of Alexandria, it had flourished at the mouth of the Nile between the 6th to 2nd centuries BC, a city twice the size of Pompeii.

He tells Josephine McDermott about the incredible artefacts he has found including the moment he realised he was at the foot of a five-metre tall statue of a pharaoh.

(Photo: The pharaoh statue discovered off the coast of Egypt. Credit: Christoph Gerigk, Franck Goddio/Hilti Foundation)